Black holes are one of the most impressive and mysterious natural forces. At the same time, they are fundamental to our understanding of astrophysics. Black holes are not only the result of particularly massive stars that become supernova at the end of their lives. They are also key to our understanding of General Theory of Relativity and are believed to play a role in cosmic evolution.
Astronomers have diligently tried for years to create a count of black holes in the Milky Way. However, new research indicates that astronomers may have missed a whole class of black holes. This goes back to a recently discovered discovery in which a team of astronomers observed a black hole of just over three solar masses, making it the smallest black hole ever discovered.
binary system ", recently published in the journal Science. The responsible team was led by Ohio State University astronomers and included members of the Harvard-Smithsonian Center for Astrophysics, the observatories of the Carnegie Institution for Science, the Dark Cosmology Center, and several observatories and universities.
The discovery was particularly notable because it identified an object that astrophysicists previously did not know existed. As a result, scientists are forced to rethink what they thought they knew about the population of black holes in our galaxy. Todd Thompson, a professor of astronomy at Ohio State University and principal author of the study, said:
"We show this indication that there is another population that we still really need to look for black holes. People try to understand supernova explosions as supermassive black stars explode as the elements are shaped into supermassive stars. So, if we could discover a new population of black holes, we would learn more about which stars explode, which do not, which black holes, which neutron stars. It opens a new field of research. "
Astronomers have long searched for black holes and neutron stars for their influence on space and time. As they are also the consequences of star-dying, they could also provide information about the life cycle of stars and the formation of elements. To do this, astronomers must first determine where black holes are in our galaxy. They need to know what to look for.
One way to find them is to look for binary systems in which two stars are locked in orbit with each other due to their mutual gravity. When one of these stars dies, the intense attraction that it generates begins to pull matter from the other star. This is evidenced by the heat and X-rays that are emitted as material from the star and accumulate on the companion of the black hole.
Previously, all black holes identified by astronomers in our galaxy were between five and fifteen solar masses. In contrast, neutron stars are generally no larger than about 2.1 solar masses, because anything larger than 2.5 solar masses would collapse and form a black hole. When LIGO and Virgo jointly discovered gravitational waves caused by a fusion of black holes, these were 31 and 25 solar masses, respectively.
This showed that black holes can appear outside the range considered normal by astronomers. As Thompson said:
"Immediately everyone was like 'wow' because it was such a spectacular thing, not only because it proved that LIGO works, but also because the masses were huge – black holes of that size one big thing – we had not seen them before. "
This discovery inspired Thompson and his colleagues to explore the possibility that there could be undiscovered objects located between the largest neutron stars and the smallest black holes To investigate, they began combining data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), an astronomical survey that collects spectra of approximately 100,000 stars throughout the galaxy.
Thompson and his colleagues studied these spectra for signs of change that would indicate if a star revolves around another object, especially if a star shows signs of a Doppler Shifting, where his spectra change between a shift to the blue end and a shift in the red wavelength, indicates that he may be orbiting an invisible companion.
This method is one of the most effective and popular methods of determining whether a star is orbiting a planetary system. When planets orbit a star, they exert a gravitational force on it that causes it to move back and forth. This type of shift was used by Thompson and his colleagues to determine if any of the APOGEE stars were orbiting a black hole.
It began when Thompson narrowed the APOGEE data to 200 candidates, which turned out to be the most interesting. He then transferred the data to Tharindu Jayasinghe, a Ohio-based academic who then used data from the OSU-operated All-Sky Automated Survey for Supernova (ASAS-SN) to compile thousands of supernovae of pictures of each candidate.
This resulted in a huge red star that seemed to orbit something much smaller than any known black hole, but much larger than any known neutron stars. After combining the results with additional data from the Tillinghast Reflector Echelle Spectrograph (TRES) and the Gaia satellite, they found that they had found a black hole that was about 3.3 times the mass of the Sun.
This result not only confirms the existence of a new class of low-mass black holes, but also provides a new method for their localization. As Thompson explained:
"We have found a new way to search for black holes, but we may have also identified one of the first of a new class of low-mass black holes that astronomers had not used to know. The masses of things tell us about their origins and evolution, and they tell us about their nature.
Further reading: OHS